This invention relates to a novel catalytic component for .alpha.-olefin polymerization which has a higher activity than conventional supported catalytic component of the Ziegler type and is capable of giving a highly stereospecific polymer in combination solely with an organo-aluminum compound and to a method for homo- or co-polymerization (hereinafter will be called (co-) polymerization for short) of an .alpha.-olefin in the presence of a catalyst system consisting of the above stated catalytic component and an organo-aluminum compound.
More specifically, the invention relates to an .alpha.-olefin polymerizing catalytic component obtained by treating, with alcohol and/or phenol, a solid product which is obtained by allowing an organo-magnesium compound expressed by a generic formula of R'MgX' (wherein R' represents a hydrocarbon group having 1 to 20 carbon atoms and X' a halogen atom selected from the group consisting of chlorine, bromine and iodine or a hydrocarbon group having 1 to 20 carbon atoms) and a halogenating agent to react with each other in the presence of an electron donor; then, by treating the treated product with a halogen-containing titanium compound either after heating it under reduced pressure or without such heating; and by treating the product further with a mixture or complex consisting of an organo-aluminum compound, an organic acid ester and a poly-siloxane. The invention further relates to a method wherein (co-) polymerization of an .alpha.-olefin is carried out in the presence of a catalyst system comprising the above stated catalytic component and an organo-aluminum compound.
Catalysts generally in use for the manufacture of stereospecific olefin polymers are of the type known by the name of a Ziegler-Natta catalyst consisting of a transition metal belonging to the groups IV-VI of the periodic table and an organo-metallic compound belonging to the groups I-III of the periodic table.
In the industrial manufacture of an .alpha.-olefin polymer such as poly-propylene poly-butene-1, etc., an .alpha.-olefin polymerizing catalytic component comprising a titanium trichloride composition as the transition metal belonging to the groups IV-VI of the periodic table or an .alpha.-olefin polymerizing catalytic component in which titanium tetra-chloride is supported by a magnesium-containing halide support or an .alpha.-olefin polymerizing catalytic component in which titanium tetra-chloride is supported by a support obtained by pulverizing a magnesium-containing halide together with an electron donor has been employed.
However, in order to obtain a highly stereospecific polymer, the use of an .alpha.-olefin polymerizing catalytic component other than a titanium trichloride composition generally necessitates use of an electron donor in addition to the .alpha.-olefin polymerizing catalytic component and an organo-aluminum compound at the time of polymerization as disclosed in Japanese patent application laid-open publications No. 48-16986 and 55-58207. Besides, as it has been well known, any deviation of the molar ratio of the electron donor to the organo-aluminum compound from an optimum value thereof, even to a slight degree, would bring about an adverse effect on the polymerizing activity and the stereospecificity of a polymer produced. Therefore, with respect to stabilization of the industrial manufacture of an .alpha.-olefin polymer, there has been a strong desire for the development of some highly active .alpha.-olefin polymerizing catalytic component that is capable of giving a highly stereospecific polymer when used in combination solely with an organo-aluminum compound.
Further, in accordance with the conventional known methods, some residue of the catalyst inevitably remains within the olefin polymer obtained. The residual catalyst presents various problems in terms of the stability, workability, etc. of the olefin polymer. These problems then necessitates provision of some additional facilities for the removal of the residual catalyst and the stabilization of the polymer. This shortcoming of the conventional methods can be obviated by enhancing the polymerizing activity expressed by the weight of the olefin polymer produced per unit weight of the catalyst. Such improvement would obviate the necessity for the facility for removal of the residual catalyst and would thus permit reduction in the cost of production required for the manufacture of an olefin polymer.
In view of this, the present inventors strenuously conducted studies for obtaining an .alpha.-olefin polymerizing catalytic component that has a higher degree of polymerizing activity than the above mentioned .alpha.-olefin polymerizing catalytic components and is capable of giving an .alpha.-olefin polymer excelling in stereospecificity. These studies have led to the present invention.